Experiement 2 Results:
Setup:
Essentially the same as the first test. 10k Embark points to purchase animals and a wagon full of food, booze, and nest boxes. I swapped some of the dorf skills around too, but that's unimportant.
In addition to all the settings from the first test, Dwarves were locked at a population of 7 to prevent migration waves from brining any extra animals to throw off my tests (Thanks to Greycat for suggesting capping at 7).
4 populations of animals were tested: Dogs, Cats, Pigs, and Peafoul. All groups were brought with 8 femals and 4 males. Females were individually penned behind closed and fobidden doors and assigned a number. In addition, Peahens were each provided a single nest box and were let sit for a month before locking the doors to assure that at least one clutch of eggs was collected priror. Further, after chick hatches the door were left unlocked for a few weeks to achieve the same end (Thanks to m-logik for peafoul suggestions).
After each birth, the producing female's number was recorded as a positive fertile, the offspring were collected into a nearby cage, and then analyzed for health at the neary butcher science lab. This was to prevent their numbers from impacting the fertility rate (Thanks to both Gigaz and Solon64 for suggestings pertaining to child population control).
The experiment was allowed to run for 2 years.
Results:
The results of this experiment were pretty clear. The dog, cat, and peafoul populations each had one sterile female and the pig population had 2 sterile females. Each of the mammal groups had 4 sets of births each, and in all cases the sterile animals repeatedly failed to produce while all other females produced viable offspring. The Peahens produced 3 hatches, and in all cases each viable pehen produced chicks with the sterile member not producing any offspring.
This is an observed rate of female sterility of just under 17% for all females.
Also of interest, it was noticed that all animal groups produced offsprin within a few seconds of each other without variation, suggesting that gestation is a set time and that impregnation happened almost simultaneously across all females in a group. In this case, gestation of all animals was exactly 6 months. This was repeatable in that all mamal births happened in 4 sets all spaced 6 months apart from each other. Peachick hatches also happened 6 months after the doors were locked, with a smidge more varience due to the time it takes for the hens to lay the eggs. This varience was still small,consisting of only a minute or two.
I used this knowledge to re-analyse my first experiment and found some interesting data there. By grouping all births within a 6 month window, I found that Infertility rates in my inital experiment were actually higher than originally reported. In the known female population of 20 animals there were 2 infertile cats, 1 infertile pig, 1 infertiile peahen, and 1 infertile rabbit. Also of note, there was a 3 month lag between the cat's first birth and the first pig birth. This coincides exactly with the first migration wave brining the grown stray boar, so the embarkation boar was actually sterile, making 3 out of the six embarked males sterile.
Thus, the overall sterility of the first experiment was roughly 30.7%.
Averaging across both experiments gives us an average sterility rate of 22%.
Analysis:
The observed sterility rate of 22% comes very close to the 25% sterility predicted by the ORIENTATION tag hypothesis. While not a confirmation, it certainly suggests more work should be done with ORIENTATION tags on animals as we gain more understanding of the tag's workings.
There is also a possibility that there is a cap on the number of pregnant animals allowed at once. If this is the case, that number is 7 because that's the most animals of any group that produced at any one time.
Also of note: The precise 6 month gestation time for all animals turns out to be a very useful piece of knowledge. While I'm sure this is not new information, I did not see it on any of the wiki pages pertaining to breeding or the meat industry, so it should be considered fror inclusion on both. This knowledge would be of great utility for determining best efficiency for breeding when running a meat industry.
There were several things not covered by this experiment that will be the focus of future work. Specifically, are children of domestic embarkation animals susceptible to the sterility bug, or is it only the embarked domestics? Are traded domestics also susceptable (there is evidence that they are) Further, are wild animals effected?
Further Work:
The next step will be testing the children. Since I have easy access to several child animals, and the current dorfs are happy enough, I will be running the next experiment as an extension of the current.
The first step of the next experiment will be to allow one final breeding cycle to allow the collection of viable child offspring.
Proceeding this collection, all fertile females will be euthenized, leaving only the sterile females. These remaining females will be given one full year (the time it takes for the offspring to reach sexual maturity) as a test for the possibility of a pregnancy cap. If any of the sterile females produces during this year, then the pregnancy cap theory can be accepted, otherwise continuted sterility of the remaining females will indicate that the cap either does not exist, or at least was not causing the sterility.
Following all child populations reaching sexual maturity, the remaining embark population will be euthenized entirely. The original experiment (8 females, 4 males of each species) will then be set up and run with the offspring of the first experiment. Any sterility observed will be recorded.
Future work:
Testing of wild animals and traded animals will need to be done at some point in the future. As will testing of the effects of the ORIENTATION tag once we figure out how it works.
A Takehome Note:
Currently, with the sterility bug effecting roughly 25% of all embarked animals (and possibly all animals), adjusting embark and capture strategies is required to produce successful meat industries.
Specifically, prior strategies revolved around bringing a 1 male and 1 or more females at embark and breeding the rest of the population. This now is a bit of a gamble. With 1 male and 1 female at embark, you have only a 56.25% chance of ending up with a viable pairing. As you increase the number of females, this chance gradually increases to 75% as the number of females tends toward infinity. Not great odds either way. Bringing 2 males and 2 females provides an 87.8% chance of producing a viable pairing, which is much better and doesn't require you to have infinite female animals. If you bring three of each, you get a 96.9% chance of having a viable pair. 2 and 2 represents a pretty good mix of value and reasonable odds, so I would reccomend this as the minumum embarkation population if you want to get breeding going right away in a new embark. If you really need to make sure you have breeding animals, 3 and 3 or higher is recommended.
It's also reccomended that you isolate animals used for breeding purposes so you can identify sterile animals and have them removed from the population. Male isolation is more difficult, but with a decent caging strategy, and careful monitorin of the 6 month gestation time, males can be tested for fertility and sterile ones removed. Whether this is worth the effort is debatable.
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Topic: New SCIENCE in breeding: Domestic Sterility Bug (Read 29309 times)